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Author: Elaine Luther, Medical Student, Ross University School of Medicine, Barbados, West Indies. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. April 2020.
Morphoea en coup de sabre is a variant of linear morphoea (a localised form of scleroderma) that is restricted to the frontoparietal region (forehead). The name ‘en coup de sabre’ (the blow of a sword) derives from the characteristic scar that indents the skin of the scalp and the underlying bone . Morphoea en coup de sabre also can cut into the brain, causing neurological abnormalities and vision problems.
Morphoea en coup de sabre is also known as frontoparietal linear morphoea (American spelling morphea), linear morphoea en coup de sabre, or just 'en coup de sabre'.
Morphoea en coup de sabre
Morphoea en coup de sabre mostly occurs in children (67%) , with a slight predominance in girls (about 2:1) . The average age of onset is 13.6 years of age .
The exact cause of morphoea en coup de sabre is unknown. It is believed to be an autoimmune inflammatory disease. There is probably a genetic predisposition, although the specific genetic factors are unknown. The trigger initiating the inflammation is usually unknown, but has been reported to include trauma, Lyme borreliosis, radiotherapy, and herpes zoster ophthalmicus. The resulting inflammatory response causes the characteristic damage.
The clinical features of morphoea en coup de sabre evolve over months to years. En coup de sabre begins with a slight hyperpigmented or hypopigmented streak on the forehead. The streak becomes indurated, evolving into a scar. As this happens, the underlying scalp and sometimes even the skull indent. As the scar grows, it reaches past the hairline into the scalp, causing linear cicatricial alopecia.
Morphoea en coup de sabre
The complications of morphoea en coup de sabre include:
The diagnosis of morphoea en coup de sabre can usually be performed clinically by noting the characteristic clinical features. Dermoscopy shows thickened telangiectatic vessels due to inflammation, fibrosis, and loss of follicles .
If necessary, a skin biopsy can distinguish en coup de sabre from similar conditions. The histology shows the classical pathological features of scleroderma [8–11].
Negative tests for anti-endothelial antibodies, antinuclear antibodies, and anti-Scl-70 can rule out other connective tissue diseases .
If borreliosis is suspected, a polymerase chain reaction (PCR) for Borrelia DNA is more reliable than testing for serum antibodies or the ELISA/Western blot [12,13].
Imaging may include ultrasound, plain X-rays, and computed tomography (CT) scans. Calvarial and intracranial abnormalities may be investigated with magnetic resonance imaging (MRI), which may show skull abnormalities, focal brain atrophy, calcification, and white matter lesions.
Diagnosis can be difficult during the early phase when the morphoea is no more than a pigmented line. Other conditions confused with morphoea en coup de sabre may include:
The goal of treatment is to prevent progression of the en coup de sabre. The most commonly used treatment is a combination of methotrexate with oral corticosteroids [14–16]. There are no published guidelines for treatment of morphoea en coup de sabre, and no standard of care. A wide range of other treatments have been successful in individual case reports.
Formulations of corticosteroids used for en coup de sabre include:
Other medications with effects on the immune reaction include:
Types of phototherapy used for morphoea en coup de sabre include:
Vitamin-based therapy reported of benefit in en coup de sabre includes:
Antibiotics have antibacterial (eg, targeting borreliosis) and anti-inflammatory (nonspecific) properties.
Once en coup de sabre is burnt out, the atrophic skin and underlying structures may undergo surgical repair. Techniques may include:
The natural history of morphoea en coup de sabre is to progress slowly over many years, then to be self-limiting. There are three phases [3,16].
The active phase of morphoea en coup de sabre features areas of active sclerosis with erythematous or violaceous borders, with or without expansion of the plaque. The goal of treatment during the active phase is to slow or stop progression with immunosuppressants.
The regression phase of morphoea en coup de sabre retains persistent sclerosis without erythema or a violaceous border. The loss of redness indicates that en coup de sabre is regressing spontaneously or due to treatment.
The burnt-out phase of morphoea en coup de sabre demonstrates no sclerosis and no erythema. The burnt-out phase signals that the course of en coup de sabre is complete, and no further damage will occur. Plastic surgery is usually deferred until the burnt-out phase .
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